US intelligence officials increasingly fear that the next terror attack on the United States will be carried out by white Americans or Europeans.

As Barack Obama and John McCain head to New York’s Ground Zero seven years after 19 Middle-Eastern hijackers brought devastation to the US mainland, counter-terrorism experts believe that any future attack will be made by terrorists with an “American face”.

They point to reports of white faces in terrorism training camps in Pakistan – the so-called “white men of Waziristan”, a reference to the remote tribal area where both al-Qaeda and the Taliban have bases.

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Experts believe that dozens of westerners have undergone such training as their leaders try to recruit non-Middle Eastern Asians, particularly ethnic Caucasians, who are less likely to attract the attention of security and law enforcement agencies.

Al-Qaeda’s recent decision to put out videos in English and a similar change on extremist “jihadi” websites have also been cited of evidence of a new strategy to find recruits who are less likely to attract the attention of security and law enforcement agencies.

Such concerns were sharpened last week after the arrest of three Germans over an alleged plot to destroy a club used by US servicemen.

Two of the three were white, ethnic Germans and all had allegedly been trained in camps in Waziristan.

“There is no bigger worry for the US counter-terrorism community than young Caucasian men who have turned to al-Qaeda,” Roger Cressey, a former National Security Council official in the Clinton and Bush administrations, told the US news network MSNBC.

Terrorism experts say such a threat has been known about even before the arrest of Richard Reid, the British shoe bomber. However, it was not until three weeks ago that a US official explicitly admitted that the government knew of such people being trained in significant numbers.